This invention relates generally to flow control valves regulating, irrespective of variations in system pressure, the quantity of fluid flow to a load.
In more particular aspects this invention relates to flow control valves of a bypass type.
In still more particular aspects this invention relates to flow control valves, in which the bypass member is controlled by a pilot valve.
In still more particular aspects this invention relates to pilot operated flow control valves of a bypass type, which permit variation in the controlled pressure differential between valve inlet pressure and the load pressure, in response to an external control signal.
The flow control valves of a throttling or bypass type regulate the flow of fluid to a load by automatically maintaining a constant pressure differential across an orifice leading to the load. The quantity of the flow is varied by the area of orifice, each area corresponding to a specific flow to the load, irrespective of the variations in the system pressure. Because of the influence of flow forces on the quantity of the controlled flow, the controlled constant pressure differential is usually selected quite high, providing a comparatively large throttling loss and therefore affecting the system efficiency. The forces necessary to vary the area of the orifice vary with the size of the valve and are usually quite high.